The present invention relates to a frequency setting method for a radio transmission apparatus of the type which transmits a signal in bursts and changes the transmission frequency burst by burst.
Radio transmission apparatuses of the type described include one which determines a transmission frequency in response to an output of a frequency synthesizer which is implemented with a PLL (Phase Locked Loop) system. Specifically, the frequency synthesizer changes the frequency of its output by changing a frequency division number. The frequency division number is given as a frequency division data signal which is applied to the frequency synthesizer. A strobe signal is also applied to the frequency synthesizer for determining the frequency division number timing.
The problem with the prior art frequency setting method described above is that the locking time necessary for the frequency synthesizer to lock the phase varies with the kind of the synthesizer, the size of change in frequency between successive bursts, and so forth. It follows that the timings for feeding the frequency division data signal and subsequent strobe signal to the frequency synthesizer have to be controlled in matching relation to a particular configuration of the apparatus.